This application relates to polycarbonate and co-polycarbonate resins, which have fluoroalkylene carbonate end groups, methods to make these polycarbonates, blends of these polycarbonates with other polycarbonates, co-polycarbonates and other thermoplastics, articles made from polycarbonates having fluoroalkylene carbonate end-groups and their blends, and uses of articles made from polycarbonates having fluoroalkylene carbonate end-groups.
Polycarbonate resins have found wide use in consumer items, the automotive industry, medical industry and the building and construction industry as well as many other markets, because of their high heat and impact resistance, and their ability to form very useful blends with other resins. These properties, along with the design flexibility that polycarbonates provide, allow them to be excellent replacements for less design-flexible and often more expensive metals, wood and other engineering materials. One very highly desirable property of many polycarbonate resins is their transparency, which, in combination with their heat resistance and high impact resistance, allows them to replace glass or other transparent thermoplastics in many consumer markets such as the ophthalmic, the optical media, the medical and the building and construction markets.
One property of polycarbonate resins, which, if it could be improved, would lead to still further expansion of the consumer and industrial uses of polycarbonate resins, is an improvement in surface properties. Molded polycarbonate resins having a high tendency to repel water on their surface would be especially useful. Such resins could find use in the ophthalmic, optical media, automotive, medical and building and construction industries and many other industries that require this property. It would similarly be desirable to improve the flame retardant properties of polycarbonate resin articles, especially those having a very thin wall thicknesses.
Fluorinated compounds are known to change the surface features of polycarbonate resins and articles formed from them. Melt blending a fluorinated compound, such as polytetrafluoroethylene, into a polycarbonate resin composition, often produces improvements in flame retardance, surface friction and water repellence, but it also typically results in an opaque or translucent appearance. Melt blends of polycarbonates and fluorinated compounds can also be different to mold because the fluorinated additive can build on the mold surface, causing degradation of the surface quality of resultant molded articles. A better method for introducing fluorinated compounds into a polycarbonate resin composition would be to chemically bond the fluorinated compound directly to the polycarbonate resin chains as co-monomer or as an end-group (the words “end-group” and end-cap” refer to monofunctional chemicals that bond to the end of polymer chains, typically inhibiting further chain growth). This approach is thought to help avoid the mold surface build-up problems mentioned above. The incorporation of fluorinated end-groups into polycarbonate resins would be a particularly simple and cost effective solution. However, a particular challenge to this approach is the tendency of many fluorinated end-group structures to undergo chemical or thermal reactions during the formation of the polycarbonate resin or in subsequent extrusion or molding operations. Such reactions can result in the detachment of the fluorinated end-cap from the polycarbonate resin chains, and resulting loss of the desirable properties.
The present invention provides for a polycarbonate resin composition having fluorinated end-groups, that are highly stable during polycarbonate resin formation reactions and subsequent extrusion and molding processes. The fluorinated end-groups can be readily incorporated into polycarbonate resins using a variety of polycarbonate resin formation methods. The molded articles from these compositions exhibit unusual and useful surface features, and possess excellent thin wall FR properties.